Traditionally, if a computer played an audio signal there was only one point of control for that signal. A user could mute, lower or raise the volume for the computer as a whole. With the introduction of Microsoft™ Windows™ Vista™, a user could control the audio level on a per application basis.
In many applications several documents can be displayed at once in a graphical user interface (GUI). In the area of GUIs, a tabbed document interface (TDI) or multiple document interface (MDI) allows multiple documents to be contained within a single window. Often tabs can be used as containers to provide different content (e.g., documents, webpages, etc.) to a user within the a single window of an application, and to allow the user to easily switch between viewing and interacting with the different content in the different tabs. TDI's and MDI's are interface styles most commonly included with web browsers, web applications, text editors and preference panes.
Conflict may arise when more than one tab wishes to play an audio signal at the same time. For example, advertisements sometimes play jingles or other audio signals. If two or more tabs include advertisements, these advertisements may attempt to play simultaneously resulting in a cacophony of noise. Typically these unwanted sound generators (e.g., advertisements, etc.) will begin playing even if their associated tab is not in the foreground or otherwise visible to the user.